Method of making power transmitting means



April 11, 1939.

c. sc'HuRR METHOD OF MAKING POWER TRANSMITTING MEANS Original FiledApril 12, 1935 Patented Apr. 11, 1939 UNITED STATES 2,15 METHOD orPATENT OFFICE MAKING POWER TRAN S- MITTING MEANS corporation of OhioOriginal application April 12, 1935, Serial No. 16,054. Divided and thisapplication July 15,

1936, Serial No. 90,746

Claims.

element or mechanism.

Another object is to provide an improved method of producing a powertransmitting element which may easily be performed.

Another object is to provide an improved method of producing a powertransmitting element which will produce articles of great accuracy.

Another object is to provide an improved method of producing a powertransmitting ele- 20 ment which will produce articles by a generativeaction.

Other objects will hereinafter appear. The invention will be betterunderstood from the description of two practical types of appa- 25 ratusand of the manner of producing them,

which includes methods embodying the invention, the apparatus beingillustrated in the accompanying, drawing, in which:

Figure 1 is a sectional view of one form of 30 steering gear produced bya process embodying the invention, taken on the axis of the drivingmember;

Figure 2 is a sectional view of the apparatus of Figure 1 taken on theline II-lI thereof;

Figure 3 is a fragmentary view showing the production of the drivingmember of Figures 1 and 2, and diagrammatically indicates parts of themechanism used in producing the same;

Figure 4 is a view similar to Figure 1 showing 40 another form ofsteering gear produced by a process constituting an embodiment of theinvention; and

Figure 5 is a view taken on the line V-V of. Figure 4 and similar toFigure 2. 45 Referring first to the apparatus of Figures 1 to 3, thesteering gear consists of a steering column or driving shaft I, enclosedin a tubular casing or steering column proper 2, and having a splinedend 3 carrying a driving member 4. The drive member 4 is of generallyspool-shaped configuration, and is provided with helico-spiral drivingsurfaces which bear some general resemblance both to a thread and to theconvolutions of a 55 worm gear, but, as will be hereinafter pointed out,

differ in certain respects from either or both these articles.

This application is a division of my co-pending application, SerialNumber 16,054, filed April 12, 1935, entitled Power transmitting means.

While in its action the drive member partakes of the nature of both a.Worm and a cam, it will be referred to, for convenience, as a drivegear.

The shaft I is supported, through drive memer 4, in bearings shown as ofthe roller type. The inner races 5 of these bearings are made integrallywith the driving member or gear 4, while the outer races 6 and l aresupported by a housing which surrounds the outer transmitting mechanism,and the rollers 8 are retained in cages 9 between the races.

The housing consists of a hollow shell [0 into which is threaded a plugII through which the i drive shaft passes and which supports the outerrace 7 of the upper bearing. The plug provides both space for theinsertion of the bearings and driving gear and means for adjusting thedistance between the outer races of the bearings to compensate for wear,as by turning it, to cause its threads to move axially in or out of thehollow shell, race I may be moved into any desired position. The plugmay be held in fixed position by any desired means, such as a set nut.

J ournalled within the shell in a bearing passing through a cylindricalextension l2 thereof is the rock shaft or driven member which is shownas consisting of a cylindrical shank l3 provided on its inner end with ahead [4 bored for the reception of a pivot pin l5 on which are mountedtwo rollers I6 and I1 engaging the surfaces of the driving gear.

The shank has a shoulder l8 bearing upon the end of a sleeve or bearingI9 and the shoulder is held in engagement therewith by a single ballbearing 20 pressed against a depression in the end of the head by a setscrew 2| threaded through a cover plate 22 forming a part of the shelland locked in position by a lock nut 23.

The outer end of the shank I3 is splined at 24 for the reception of anarm 25 which may be connected to the drag link which is fastened tosteering arms customarily carried by the stub axles on which the wheelsof the vehicles are mounted.

The arm upon the rock shaft is secured thereto by a nut 26 threaded ontothe end of the shaft.

screw or lock The bearing i9 is shown as provided with an eccentricbore, so that rotation of the bearing will move the rock shaft toward orfrom the the axis of the grinding wheel arranged parallel to that of thedrive gear. This wheel contacts surfaces 30 and 3| of the driving gear.

If, now, the wheel, while being driven, be rotated about an axis 32,corresponding to the axis of the rock shaft, and at the same time thedriving gear be rotated about its own axis, it will be apparent that asthe wheel movesfrom the position indicated at 29 to that indicated at 33the left hand edge of the cutting surface moves toward the axis 34 ofthe driving member and to the right, while the right hand edge movesaway from this axis and also to the right, these surfaces each tracing aconvolution which progresses both radially and axially along the drivingmember. If the motions of both the grinding wheel and driving member becontinued from the position shown at 33 to that shown at 35, thesesurfaces are prolonged to constitute another convolution.

If, now, the rotation of both grinding wheel and driving member bereversed, these parts first retrace, their path through the positionsabove referred to and thence proceed to a position 36 in which the lefthand edge of the wheel contacts surface 31 and the right hand edgecontacts with surface 38.

It will be apparent that the two surfaces gen erated meet each other atsome points at right angles, and at others at relatively obtuse angles,

' so that a tool having a rectangular cutting por- Obviously, while agrinding wheel has been disclosed, it will be apparent that astraight-edged turning tool, a milling cutter having a cylindricalcontour, or other cutter, either possessing or capable of generating astraight line, might be used.

As in the steering of a vehicle, thevehicle remains on a straight coursefor by far the greater.

portion of the time, the rollers will contact the parts of the drivinggear at or near surfaces 30 and 3] most of the time, and wear willnaturally be greater at these points than at the ends or center of gear4.

It is therefore desirable that the rollers fit more tightly at points3|] and 3|-than-elsewhere. This result may be obtained by using agrinding wheel or the like of greater diameter than the rollers,

as the surfaces of the part 4, being eccentric or spiral in shape, willcontact the surface of the cutting tool outside the plane defined by thegear and tool axes. Also this result may be conveniently obtained orincreased by rotating the tool about center slightly more remote fromthe axis of the drive gear 4 than that which will be assumed by the rockshaft.

In the apparatus shown in the first three figures, it is obvious thatthe driving shaft may make something over two revolutions, while therock shaft is moved through considerably less than one revolution, itbeing impracticable to move the rock shaft beyond the point where bothrollers are in engagement with the driving geai.

In Figures 4 and 5, the driving gear is formed in the same manner asthat shown in the first three-figures, it having however two lessconvolutions of the cam surfaces and thereby being reduced both indiameter and in length.

The rock shaft in this instance is provided with a head H4 having twointegrally formed trunnions H6 and III or bearing surfaces which engagethe cam surfaces of the driving gear at points I30 and HI correspondingto 30 and 3| on the driving gear of the first three figures, so that thesame amount of travel of the rock shaft and head is provided with thesame number of rotations of the drive shaft as was the case in the firstillustrated embodiment.

The production of the driving member in the last two figures may be muchmore expeditiously performed for two reasons, one; that two lessrevolutions of the drive member must be made in producing the same, and,two; that all surfaces may be completely formed by a single tool withoutits fouling the edges of the outer convolutions.

The adjustment shown in Figures 4 and 5 are the same as those of Figures1 and 2, excepting that a clamping bolt I21 has been provided to lockthe bearing in position. Corresponding parts, not specifically describedin connection with these two figures, are provided with referencenumerals corresponding to those of the first three figures, butincreased by 100.

While I have described the methods which embody my invention in someparticularity, obviously many others will readily occur to those skilledin this art, and I therefore do not limit myself to the precise detailsshown and described herein, but claim as my invention all embodiments,modifications and variations coming within the scope of the appendedclaims.

I claim:

1. The method of generating surfaces which comprises rotating a formingtool having a cylindrical working surface about its axis, oscillatingthe tool about a second axis lying in a plane normal to the firstmentioned axis, simultaneously rotating a work blank being operated onby the tool about the axis of the blank, the rotation of the work blankand the oscillation of the tool being in predetermined timed relation,and thus causing the cylindrical surface of the tool at one side of saidplane to generate one helico-spiral surface and the cylindrical surfaceof the tool on the other side of said plane to generate a secondhelico-spiral surface, said helico-spiral surfaces intersecting eachother.

2. The method of generating surfaces which comprises rotating a formingtool whose working surface is a locus of a plurality of straight linesrevolved about a non-perpendicular axis, oscillating the tool about asecond axis lying in a plane normal to the first mentioned axis relativea work blank simultaneously rotating the work blank about its axis, therotation of the work blank and the oscillation of the tool being inpredetermined timed relation, and thus causing the tool at one side togenerate one helico-spiral surface, on the other side to generate asecond helico-spiral surface,,said helico-spiral surfaces intersectingeach other.

3. The method of generating surfaces which comprises arranging a toolhaving a cutting surface defining a straight line lying in a planeincluding the axis of a piece of work, relatively oscillating the tooland work about an axis normal to the said plane and remote from both theaxis .ofthe work and from said straight line, simulcluding the axis of apiece of work, relatively oscillating the tool and work about an axisnormal '20 to the said plane and remote from both the axis the work andfrom said straight line, simultaneously rotating the work about itsaxis, the working surfaces of the tool defining said line and extendingto both sides of, the intersection 25 of said line with a perpendicularthereto from the axis about which the tool is oscillated, correlatingthe oscillation of the tool and the rotation of the work atpredetermined relative velocities, and causing the tool at oppositesides of the said perpendicular to form two intersecting helicospiralsurfaces upon the work.

5. The method of generating surfaces which comprises arranging agrinding wheel having a cylindrical peripheral working surface defininga straight line lying in a plane including the axis of a piece of work,relatively oscillating the grinding wheel and work about an axis normalto the said plane and remote from both the axis of the work and fromsaid straight line, simultaneously rotating the work about its axis, theworking surfaces of the tool defining said line and extending to bothsides of the intersection of said line with a perpendicular thereto fromthe axis about which the tool is oscillated, correlating the oscillationof i the grinding wheel and the rotation of the work at predeterminedrelative velocities, and causing the grinding wheel at opposite sides ofthe said perpendicular to form two intersecting helicospiral surfacesupon the work.

- CHARLES H. SCHURR.

